In U.S. Pat. No. 3,631,325 issued to Charles F. Wenz and assigned to the assignee of the present application, which Patent is hereby incorporated by reference there is described a module in which the heat exchanger comprises a block of thermally conductive material in which is formed parallel notches into which may be inserted the edges of a printed circuit board. Located in each of the parallel notches is a series of leaf springs which bear against the printed circuit card and hold the edge strip in intimate contact with the walls of the notches formed in the heat exchanger. The Wenz patent attempts to overcome the insertion and withdrawal force problem by coating the edge strips with a suitable material having good thermal conductivity and a low coefficient of friction.
The present invention is considered to be an improvement over the invention described in the aforementioned Wenz patent. Rather than providing leaf springs as in the Wenz patent, the arrangement of the present invention includes a means whereby the spring tension which normally urges the edges of the printed circuit boards in contact with the surface of the heat exchanger may be removed so that the printed circuit board can be inserted into or removed from the heat exchanger with very little force or pressure.
In accordance with the teachings of the present invention, there is provided a heat exchanger in the form of a block of thermally conductive material in which a plurality of parallel notches are formed and which are adapted to receive the edges of a plurality of printed circuit cards having thermally conductive edge strips thereon. A plurality of helical springs are provided which have one end thereof secured to the vertical segments of the block located between adjacent notches and the other end secured to a movable release strip. The release strip, in turn, is connected to a lever and cam arrangement such that when the lever is moved to a first position, the spring members secured thereto are compressed to the point where they no longer occlude the notches in the heat exchanger block adapted to receive the printed circuit card edges. When the cam lever is moved to the opposite position, the spring tension is released and these helical springs force the edge strip of the card into intimate contact with the sidewalls of the notches in the heat exchanger block.
The present invention permits many printed circuit boards, which may already be plugged electrically into a backpanel, to be simultaneously inserted into the grooves of a heat exchanger which may be disposed on the side of the printed circuit boards opposite from the backpanel.